A power conversion device for driving a motor rectifies alternating current supplied from an AC power source, converts rectified direct current into alternating current, and drives a motor, which generally includes a brake transistor that consumes regenerative energy generated during deceleration of the motor by allowing current to flow to an external resistor. Further, a motor-driving power conversion device is required to include a configuration that makes it operate stably even when the voltage of the AC power source fluctuates and the voltage falls and to include a configuration that makes it possible to improve the torque and output of the motor.
In the related art, a configuration has been disclosed of an electric power steering device that drives an electric power steering motor in which operations between boosting and regenerative operations can be switched while in use (for example, Patent Literature 1).